This invention relates generally to disk drives or disk files employing aerodynamically releasable locks, operable when the disk drives are not operating, to lock the actuator assembly against movement with the magnetic heads thereon positioned in a landing zone on the disks.
Typical disk drives or files are illustrated in U. S. Pat. Nos. 4,538,193, 4,647,997 and 4,692,892.
These disk drives each comprise a disk stack. Magnetic heads on an arm stack, forming part of an actuator assembly, are moved across the tracks and positioned by the actuator assembly at a selected track, in track seeking and track following modes operation. When the disk drive is to be stopped, the actuator assembly moves the magnetic heads to a location outside of the disk areas in which data tracks are recorded, to a disk area called the landing zone, usually near the center of the disks. When the disk drive is to be stopped the actuator assembly moves the magnetic heads to the landing zone. When the drive is de-energized and the disks spin down, the magnetic heads land and slide on the disk surfaces in the landing zone. To prevent damage to the tracks recorded on the disks, resulting from unwanted actuator assembly movement, dragging the magnetic heads across the tracks, when the disk drive is inactive, each disk drive in the referenced patents comprises an aerodynamically operated lock for the actuator assembly. The respective aerodynamically operated locks are pivotally mounted and have one or more vanes individually projecting between adjacent disks in the disk stack. The aerodynamically operated locks are rotated to a position unlocking the actuator assembly by the force of moving air impinging on the vanes, generated as a result of disk rotation. Spring coupled or magnetically coupled torques rotate the locks to move a projection or latch on each of the aerodynamically operated locks, in the absence of aerodynamic forces on the vanes when the disk drive is stopped, to a position engaging a notch or catch on the actuator assembly to secure the actuator assembly in a position with the magnetic heads in the landing zone.
As the disk drives are reduced in size, the air volume between the disks diminishes due to the reduction in the axial spacing of the disks and due to the reduction in disk diameter. For a given rotational speed, the reduction in the diameter of the disks also reduces the tangential velocity of the air. The volume of air flow generated per unit of time, by rotation of the disks in the small disk drives, is therefore significantly diminished. Additionally, the moveable air vanes projecting between the adjacent disks are reduced in size both in length and in width, reducing their surface area. The reduction in aerodynamic force per unit area together with the reduction in air vane surface area, diminishes the total aerodynamic force to a point where operation becomes marginal.
To be effective, the air vanes must have small clearance with adjacent disk surfaces and be of low mass. This requires precise support, positioning and journaling of the actuator lock to avoid contact of the vanes with the disk between the extremes of actuator lock rotation, and sufficient air vane rigidity to avoid air vane deflection and contact with the adjacent disk surfaces, in the presence of forces due to acceleration. This places stringent requirements on fabrication to achieve the necessary mechanical precision and stability.